New Respiratory Syncytial Virus Prevention Options on the Horizon for Older Adults

Nine respiratory syncytial virus (RSV) prevention candidates are in phase 3 trials, including several vaccines for older adults. Researchers reviewed the pipeline in an article published in The Lancet Infectious Diseases. 

“RSV prevention appears to be on the horizon with market access expected for nirsevimab within the next 12 to 24 months as of July 2022,” wrote an international team of researchers. “This approval might be followed shortly by approval of a maternal vaccine and a vaccine for older adults.”

For the protection of older adults, vector, subunit, and nucleic acid approaches are in late-phase development. 

MVA-BN-RSV is a vector vaccine that produced elevated antibody responses in older adults for 6 months in a phase 2 trial. Researchers are preparing a phase 3 trial to further study the vaccine’s efficacy and safety.

Ad26.RSV.pre-F, another vector vaccine, demonstrated 80% (95% CI 52 to 93) efficacy against RSV lower respiratory tract infections in a proof-of-concept study conducted among older adults. A phase 3 trial is underway to study Ad26.RSV.pre-F in 23,000 older adults across two RSV seasons.

RSVPreF is a subunit vaccine currently being tested in a phase 3 trial. The trial, which began in the latter half of 2021, involves approximately 30,000 healthy and high-risk older adults.

RSVpreF3 is another subunit vaccine being studied in combination with AS01 adjuvant. An interim analysis of the phase 3 trial indicated RSVpreF3 is efficacious for reducing RSV lower respiratory tract infection. 

The mRNA-1345 vaccine produced antibody responses with a favorable safety profile in a phase 1 trial. Investigators are continuing to study mRNA-1345 in a phase 2/3 trial of 34,000 adults aged 60 years and older.

“If all the ongoing phase 3 trials generate positive results, relative efficacy and safety trial data, delivery strategies, and costs might determine vaccine uptake for different maternal and older adult candidates,” researchers said.

In all, 33 RSV prevention candidates are in current clinical development. The authors credit a better understanding of the epitopes targeted by highly neutralizing antibodies for guiding the transition from empirical to structure-based vaccine and monoclonal antibody design.

“Overall, we are at an exciting phase of vaccine and monoclonal antibody development in which RSV prevention is within reach,” the authors wrote. “It is likely that multiple immunization strategies with complementary value, unique advantages, and use-case scenarios will shape the RSV prevention landscape.”

Reference:
Mazur NI, Terstappen J, Baral R, et al. Respiratory syncytial virus prevention within reach: the vaccine and monoclonal antibody landscape. Lancet Infect Dis. 2023;23(1):e2-e21. doi: 10.1016/S1473-3099(22)00291-2